Hydrostatic Travel Drive and Method for Controlling the Hydrostatic Travel Drive

Patent metadata

Field	Value
Publication number	US-2020003301-A1
Application number	US-201916455200-A
Country	US
Kind code	A1
Filing date	Jun 27, 2019
Priority date	Jun 29, 2018
Publication date	Jan 2, 2020
Grant date	—

Abstract

A hydrostatic travel drive includes a hydraulic pump for the purpose of supplying pressure medium to a hydraulic motor of the travel drive that can be coupled to an output, which pump can be coupled to a drive machine. The hydraulic pump has an actuating cylinder with at least one cylinder chamber and a swept volume which can be adjusted via the actuating cylinder, and at least one electrically activatable pressure valve via which the cylinder chamber can be charged with an adjustingly active actuating pressure. The travel drive further includes device via which a pressure of the hydraulic pump can be limited by means of influencing the actuating pressure.

First claim

1 . A hydrostatic travel drive comprising:
a hydraulic pump coupled to a drive machine and configured to supply pressure medium to a hydraulic motor of the hydrostatic travel drive that is coupled to an output of the hydrostatic travel drive, the hydraulic pump having an actuating cylinder that includes at least one cylinder chamber and is configured to adjust a swept volume of the hydraulic pump; at least one electrically activatable pressure valve configured to charge the at least one cylinder chamber with an adjustingly active actuating pressure; and a device configured to limit a pressure of the hydraulic pump by influencing the actuating pressure, wherein the device is configured to limit the pressure the pressure in a controlled manner.

2 . The hydrostatic travel drive according to claim 1 , wherein the device is an electronic control unit.

3 . The hydrostatic travel drive according to claim 1 , wherein the device includes a characteristic curve of the hydraulic pump, the characteristic curve representing the actuating pressure as a function of a limit of the pressure and at least of the swept volume of the hydraulic pump or of a variable of the hydraulic pump representative of the swept volume.

4 . The hydrostatic travel drive according to claim 1 , wherein the device includes a characteristic map of the hydraulic pump, in which the actuating pressure is described as a function of the pressure and at least of the swept volume of the hydraulic pump or of a variable of the hydraulic pump representative of the swept volume.

5 . The hydrostatic travel drive according to claim 3 , wherein the actuating pressure is described in the characteristic curve as a function of a rotational speed of the hydraulic pump.

6 . The hydrostatic travel drive according to claim 4 , wherein the actuating pressure is described in the characteristic map as a function of a rotational speed of the hydraulic pump.

7 . The hydrostatic travel drive according to claim 3 , wherein the device is configured to determine a maximum permissible actuating pressure from the characteristic curve.

8 . The hydrostatic travel drive according to claim 4 , further comprising:
a request interface configured be signal-connected to the device and configured to transmit a speed request to the device.

9 . The hydrostatic travel drive according to claim 4 , wherein the device is configured to determine a necessary actuating pressure necessary according to the speed request from the characteristic map.

10 . The hydrostatic travel drive according to claim 9 , wherein the device is configured to at least one of determine and select a lower of a maximum permissible pressure and the necessary actuating pressure.

11 . The hydrostatic travel drive according to claim 1 , wherein the device includes a valve characteristic curve of the pressure valve, the valve characteristic curve describing an electric activating current as a function of the actuating pressure.

12 . A method for limiting a pressure of a hydraulic pump of a travel drive that includes (i) the hydraulic pump, which is coupled to a drive machine and configured to supply pressure medium to a hydraulic motor of the hydrostatic travel drive that is coupled to an output of the hydrostatic travel drive, the hydraulic pump having an actuating cylinder that includes at least one cylinder chamber and is configured to adjust a swept volume of the hydraulic pump, (ii)at least one electrically activatable pressure valve configured to charge the at least one cylinder chamber with an adjustingly active actuating pressure, and (iii) a device configured to limit a pressure of the hydraulic pump by influencing the actuating pressure, the method comprising:
influencing the actuating pressure with the device so as to controllably limit the pressure of the hydraulic pump.

13 . The method according to claim 12 further comprising, with the device, at least one of:
determining a traction mode or braking mode of the travel drive;
determining a direction of travel of the travel drive; and
selecting at least one of a characteristic curve and a characteristic map of the hydraulic pump and/or of the pressure valve in dependence on the determined mode and/or on the determined direction of travel.

14 . The method according to claim 12 , further comprising:
determining, with the device, a maximum permissible actuating pressure from a characteristic curve of the hydraulic pump, the characteristic curve representing the actuating pressure as a function of a limit of the pressure and at least of a swept volume of the hydraulic pump or of a variable of the hydraulic pump representative of the swept volume.

15 . The method according to claim 14 , further comprising:
determining, with the device, a necessary actuating pressure according to a speed request from a characteristic map of the hydraulic pump, the characteristic map representing the actuating pressure as a function of the pressure and at least of a swept volume of the hydraulic pump or on a variable of the hydraulic pump representative of the swept volume.

16 . The method according to claim 15 further comprising:
determining, with the device, a lower of the necessary actuating pressure and the maximum permissible actuating pressure;
based on the determined lower of the necessary actuating pressure and the maximum permissible actuating pressure, determining, with the device, an electric activating current of the pressure valve from a valve characteristic curve of the pressure valve, the valve characteristic curve representing the electric activating current as a function of the actuating pressure; and
with the device, activating the pressure valve with the determined electric activating current.

Assignees

• Bosch Gmbh Robert

Inventors

• Mueller Matthias
• Frasch Michael
• Mutschler Steffen
• Lenzgeiger Ulrich

Classifications

• F16H61/4008 Primary

  Control of circuit pressure · CPC title

• F16H63/40

  comprising signals other than signals for actuating the final output mechanisms · CPC title

• F04B49/002 Primary

  Hydraulic systems to change the pump delivery · CPC title

• F16H61/4192

  Detecting malfunction or potential malfunction, e.g. fail safe · CPC title

• F16H61/433

  Pump capacity control by fluid pressure control means · CPC title